I will follow up on that, it was not the case even quite recently. If they really have rewritten all code, then great - I have no problem with this!
Replacing code whose license you don't want is definitely a fair-and-square way to manage a project and change the overall terms under which you can distribute it. (As it happens, that tactic is often essential to efforts to open-source formerly proprietary projects, too.)
Re:OpenTF Announces Fork of Terraform
by therealpygon on Friday August 25, 2023 @11:09PM
(#37269611)
*Provided that the replacement is not simply a rewritten version of the same code that achieves the same result through overwhelmingly similar methodology.
The function of code is explicitly not protected by copyright and the breadth of this exemption was clarified and expanded by Google vs Oracle.
The LibreOffice project faced a similar dilemma and have carefully kept the old licenses in their files, and new license in new code in new files.
There's are only 2 .go files left in the hashicorp/terraform.repo which still have MPL-2.0 in their license headers, so either there was no community code left, so either there are virtually no such contributions left in Terraform or they have in fact attempted to relicense code.
This looks like relicensing to me: https://github.com/hashicorp/terraform/commit/53c34ff49cfbc1...
Btw, no file that you still show up in `git blame` for has an MPL notice header.